145 



FAMILY TRlGONIIDiE. 



GrENUS TkIGONIA. 

 SYNOPSIS OF SPECIES. 



Transversely ridged on tlie anterior two-tHrds o£ the valves ; 

 posterior slope radially ridged. 

 E^idges plain. T. semiundulafa. 



E/idges witli tubular projections. T. tuhulifera. 



Whole surface of valves radially ridged. 



Eibs acute with spinous tubercles. T. acuticostata. 



Eibs thick, anterior ones with blunt tuberculations. 



T. Howitti. 

 Trigonia semmndulata, McCoy. 

 Beferences. — Geological Magazine, vol. 3, p. 481, and Pal. 

 Victoria, Dec. II., pi. xix., figs. 4, 5. 



Localities. — Victoria : very abundant in the sandy beds o£ 

 Bird Eock Bluff, near Geelong {McCoy); Muddy Creek {B.T.); 

 Tasmania : Table Cape ! {B. M. Johnston) ; South Australia : 

 silicified sandstone blocks in the sharp sands underlying the 

 pebble bed at Gawler (B. T.J. Also quoted by Hutton from 

 the Pareora Series at Awamoa, ISTew Zealand. 



Trigonia tubulifera, Tate, Plate xi., figs. 13a — 135. 



Beference. — Southern Science Eecord, January, 1885, p. 3. 



Shell minute, quadrate ; the flattish posterior area with about 

 16 thin radial ribs beset with truncate tubular projections; the 

 remainder of the surface with about 20 concentric ribs similarly 

 ornamented. 



The tubular projections are short though conspicuous, and ^ 

 are separated one from the other by intervals not much wider 

 than the tubes. Only two examples have occurred to me — one, 

 a left valve, from Schnapper Point, on which the two areas are 

 well-marked, the other, a right valve, from Muddy Creek, has 

 the anterior area so masked by the long tubular projections as 

 to conceal the concentric arrangement of the ribs. 



Lengtli and height, about 5 millimetres. 



Trigonia acuticostata, McCoy. 



Beferences. — Geological Magazine, vol. 3, p. 482, and Pal. 

 Victoria, Dec. II., pi. xix., figs. 1, 2. 



Localities. — Muddy Creek and Mordialloc. Victoria (IIcCoi/); 

 oyster beds of the Upper Murravian at the North-west Bend 

 Head Station, E. Murray, in South Australia (B. T.) Casts, 

 probably of this species in beds of the same age at Tickera near 

 Wallaroo, and at Aldinga. 



It has been reported by Prof. McCoy (Ann. and Mag, Xat. 

 Hist., 1876, p. 273) living in Bass Straits. 



